Our Process

Techniques of Stained Glass

The methods of the stained glass craft have changed very little since the Middle Ages. The handcrafted stained glass a window involves many stages and is a lengthy process. Phil was recently asked how stained glass has changed during the past 200 years and his answer was “electricity”. A stained glass window is made of pieces of glass assembled together with lead; often traditional stained glass windows are painted. The art of stained glass is unique because of the relationship between the glass and light. Light is needed for the stained glass to come alive and be vibrant.

A paradigm shift appears to be the new approach for today’s companies in order to adapt to the changing economy, seeking a cost-cutting approach toward business in order to survive. Watkins Stained Glass Studio has the philosophy of a contrasting paradigm shift. Our studio still operates as a century ago, creating ART, one of a kind and a project at a time, rather than mass-producing to put out a product. Here a standard of excellence, the finest glass, attention to detail and the true expert master craftsmanship can still be found. We invite you to call for an appointment.

The process of stained glass will be defined and described in the following stages.

The Sketch

The sketch is the first of the many stages of a stained glass window. This represents the preliminary step in the creation of a stained glass window and becomes the master plan of the project. First, the design is determined, and then the sketch is drawn as a miniature version of the window, generally in the 1-inch to 1-foot scale. A custom sketch will be designed and hand drawn for each customer, not to be repeated. The sketch will provide an accurate impression of the color and light of the final window appearance. Any changes can be made at this time. Once the sketch is agreed upon and approved, the project begins.

We recommend that customers visit Watkins Stained Glass Studio to view the 1000’s of photographs and sketches of stained glass windows previously made by the studio to help them decide on their design preference; customers can also bring in their own design ideas. Each window or set of windows is one of a kind and will not be duplicated.


The Cartoon is a full size drawing of the final design that then becomes the work drawing for the fabrication of the window. The cartoon is squared-up for the exterior size and drawn by hand in the studio with precise scaled measurements according to the sketch. The cartoon will be used for the glass selection, which is the careful assignment of a glass color and texture for each piece of glass in the window. The cartoon will serve as the work drawing on the workbench from which the stained glass is fabricated.

Glass Selection and Coloration

The color selection is an essential element for a successful stained glass window, it is important to select just the right glass, color and texture. A color scheme is selected from color palets that contain many shades of glass from the studio glass inventory of about 25,000 square feet of glass. Pieces of glass are held up to daylight to see the effect of the colors together and seek interesting textures or variations within a sheet of glass. Since the color selection is an extremely important part of the project, a great deal of time and consideration are spent on this phase of the project. Every piece of glass in the inventory has a separate identification number. The cartoon will be used to indicate the assignment of the glass numbers.

Antique Glass

This is hand or mouth-blown providing translucency, a variety of color and textures and seeds from the air blowing process. The methods and formulas used to make this glass are very similar to that done to create glass during medieval times. This glass had most often been made in Europe. Sadly nearly all of these fine glass producers have gone out of business during the past 80 years.

Cathedral Glass

This is machine rolled rather than hand-blown, which makes it less expensive. It is mechanically produced rather than hand made. These mechanically produced surface patterns aid in light diffusion. There are many textures available and hundreds of colors from which to choose.

Opalescent Glass

This is an opaque glass with milky appearance and swirled colors within the piece of glass. It had been used extensively in older stained glass windows. It is also used because it provides maximum light diffusion and is difficult to see through, thus allowing non-glare and privacy.


When the cartoon has been completed and glass selections have been made, the next step is the Patterning. The white paper cartoon is placed over thick brown pattern paper with a layer of carbon paper between the cartoon and the pattern paper. The cartoon is re-drawn with a red pen down the exact center of each lead line, so as to transfer the cut-lines onto the thick pattern paper. The tracing of the lead lines of the cartoon delineates each individual pattern piece.

These thick paper patterns are then cut with special three-bladed pattern shears that simultaneously cut out a very narrow strip of paper. This narrow strip of paper corresponds to the width of the lead came core, thus eliminating the paper equal to the heart of the lead came that goes between the glass. Once the paper patterns are cut, they are sorted according to glass color number and are ready to be used to cut the glass.

Glass Cutting

Cutting the glass from the pattern pieces is the next step in the stained glass process. The appropriate thick paper pattern is placed on desired color of glass. Each piece of glass is hand cut to the shape of the pattern using a steel or carbide wheel glass cutter specifically designed to cut stained glass. The cut pieces of glass are placed onto the cartoon that has been secured on the workbench that becomes the work drawing ready for the glazing process.


Painting on stained glass is done to give the glass detail, shading and texture. The two common types of painting procedures are done with matt and trace. Special stained glass paints are used to paint the glass that have special qualities that react well with the glass and the kiln firing process. Paint used on the glass throughout the centuries was normally vitreous. Stained glass paint consists of a mixture of finely ground iron oxide or copper oxide, powdered glass, mixed with borax as a flux. Silver stain is often used for finely painted religious stained glass windows and is painted on the reverse side of the glass.

Dozens of different brushes are used to apply the paint to the glass, as well as giving the glass a special look and texture. There are brushes for lines, for matting, regular shading or gradations of shading and stippling, among other techniques; the Badger Blender is a most important brush. The painting is done on a glass light table. Our painting technique is similar to that of 800 years ago. Phil Watkins and Joan Chandler have been painting stained glass for decades are both recognized Master Glass Painters.

Kiln Firing

After the glass has been painted, it will carefully be placed in the kiln for firing. Firing is the process of heating the painted glass in a kiln so that the paint and glass are smoothly and permanently fused together. Properly fired glass will last for centuries, just like the work of the medieval masters. Much skill and experience are necessary for the craftsman to properly operate the kiln, as temperatures vary between the type of glass, imported European antique glass versus American domestic glass, as well as the thickness and density of the glass. There are high fire paints and low fire paints that all require different temperatures. Different kinds of glass should be fired separately to accurately fire and for best results. Establishing the exact moment when the glass and the paint have fused is of prime importance.

Once the kiln has reached the desired temperature, it is then slowly annealed or cooled. Often the painting and firing process will be repeated numerous times until the designed painted look, depth and color intensity is achieved. When the glass painting is complete and the glass has cooled, the piece of glass is returned to its original position on the cartoon.


Waxing is a process used for a painted window. The cut glass is waxed onto a “light wall” with beeswax, in the same position as it was drawn on the cartoon. The glass is then painted with special stained glass paints. The process allows painting brush strokes to follow through the various pieces of glass and gives the artist a chance to view the window with light shining through it. Sometimes a portion of a window may also be waxed up to see how the colors blend and how he window will look in daylight. The process of waxing up the painted glass was used for The Last Supper window.


After the glass has been cut and sometimes painted, it will be placed back on the cartoon work drawing that has been nailed down on the workbench; the glass is now ready to be assembled into the lead came. The lead is a very malleable and comes in various thicknesses and widths. The “H” lead is stretched then cut precisely with a lead knife or lead dyke and tightly fitted around each of the pieces of glass, then nailed to hold in place. This is continued until the lead and glass are in its proper place according to the outline drawing on the cartoon below.

After the lead has been cut and glass is in place, flux is applied to each of the many lead joints then soldered together with a soldering iron. Both sides of the window must be soldered then the flux must be cleaned off the window. The function of the lead came is to give the stained glass integrity and structure, as well creating an artistic design within the window. Bars may be added for stabilization. (The glazing process is very similar to that of the Medieval times, however, now we have the use of electricity; centuries ago the soldering irons were heated, thus the term “too many irons in the fire” was a relevant term.)


When the glazing process has been completed, the window is moved to another bench for cementing. Special hand made stained glass cement is then applied to the window, carefully pushing it between the space between the glass and the lead and on both sides of the window. Once the cement has been brushed into the window, it is then cleaned off the surface. After a few days when the window has somewhat dried, the surface along the lead lines is picked to remove any visible cement. This cementing process greatly strengthens, stabilizes and waterproofs the stained glass window.


The final process is the stained glass installation. Often the window has a piece of window glass or Tempered glass on the outside. The new window will usually be installed from the inside and placed against the existing clear glass using various methods of securing the window in place. It is not necessary to make these into commercially insulated units, as often this creates a variety of problems and Watkins windows do not require additional stabilization. Stained glass windows made by Watkins Stained Glass will provide beauty for generations to come.

Although there are many studios and individuals producing stained glass windows, it is the quality of artistic design, intricate painting and skilled master craftsmanship that set Watkins Stained Glass apart and make these custom windows so special and long lasting.


Restoration is the process in which an old stained glass window is repaired using reverse techniques from which the window was originally made to carefully take it apart in areas that are damaged. When the glass is broken, we attempt to use the same original glass in color and texture (we do have an extensive supply of 50-100-year-old glass at the studio passed down through the generations). We are also quite fortunate to have the matching lead came that was originally used in historic windows. The desired end result will be a stained glass window that has been repaired in such a way that it looks as if it were brand new a century ago. There is a great importance placed on the historical value of the window. We strive to restore damaged areas of the window rather than replace them, which requires a high level of master craftsmanship, skill, experience and ingenuity. Windows are not re-leaded by properly restored using the proper preservation techniques, repairs are reversible and there is always an emphasis on original materials. The studio is now restoring some of the stained glass windows made by the Watkins craftsmen 80 to 120 years ago; these newly restored windows should be expected to last another 100 years. We work hard at creating and restoring windows that will have sustainability into the next century.